Foundry molding machine



April 1969 L. F. MILLER ETAL 3,439,733

FOUNDRY MOLDING MACHINE Filed Dec. 27, 1965 Sheet of e INVENTORS LEON EMILLER "1 HENRY J. HERBRUGGEN BY awn 7141 0 ATTORNEYS A ril 22, 1969 L.F. MILLER ETAL 3,439,733

FOUNDRY MOLDING MACHINE Filed Dec. 27, 1965 Sheet of e 1 m 8 W 07 i m" iI04 JET .3

I04 l I03 n fa" 101 "\IOS "mm F M :34 I34 INVENTORS L LEON E MILLER gHENRY J. HERBRUG'GEN BY ammd a 0 ATTORNEYS April 22, 9 L. F. MILLER ETALFOUNDRY MOLDING MACHINE 3 I of 6 Sheet Filed Dec. 27, 1965 n2 hrINVENTORS LEG/V F. M/LLER HENRY J. HERBRUGGE/V dmflmyhydflmwulfiATTORNEYS April 1969 L. F. MILLER ETAL 3,439,733

FOUNDRY MOLDING MACHINE Filed Dec. 27, 1965 Sheet 4 of e HEN/'7) J.HERBRUGGE/V ATTORNEYS April 22, 1969 L. F. MILLEF: ETAL FOUNDRY MOLDINGMACHINE Sheet Filed Dec. 27, 1965 ATTORNEYS On? mm Hula Mm @mm :I. J.

21 mmw mmmA 0 N m: 55 mnmv L H April 22, 1969 L. F. MILLER ETAL3,439,733

FOUNDRY MOLDING MACHINE Filed Dec. 27, 1965 Sheet 6 of 6 :95; I96: 1 44I56 J f lh 5 l57 F/K\ A a 1 L91. I g? 4 J l I n g ag, I I 217 d falsfJg. [E7

. INVENTORS LEON F MILLER HENRY J. HERBRUGGEN ATTORNEYS United StatesPatent 3,439,733 FOUNDRY MOLDING MACHINE Leon F. Miller, Rocky River,and Henry J. Herbruggen, Westlake, Ohio, assignors to TheSherwin-Williams Company, a corporation of Ohio Filed Dec. 27, 1965,Ser. No. 516,634 Int. Cl. B22c 5/08, 7/00, 5/04 U.S. Cl. 164200 9 ClaimsABSTRACT OF THE DISCLOSURE This invention relates generally as indicatedto a foundry sand forming machine and method and more particularly to aprocess and machine for producing sand molds or cores by passing hot airtherethrough.

In conventional hot box core or mold making machines, gas burners aregenerally employed producing a flame which impinges directly on the coreor mold box. These machines work at curing or heating temperatures inthe range of approximately 600 to 700 F. If one of these many burnersemployed is not functioning properly, the heating of the box will beuneven and the box may shrink or distort causing the production ofinaccurate cores or molds, broken cores or molds, or improperly curedcores. Moreover, such systems generally shorten the life of theexpensive patterns or boxes employed. One of the most economical andeasily workable materials which can be employed for a core box isaluminum, but which cannot be subjected to such extreme temperatures andproduce continually accurate molds or cores. Moreover, long cure timesare still required since the high temperatures simply transfer the heatfrom the heated box inwardly to the interior of the core or mold.

Often times conventional hot box machines require special core removalequipment since the high temperatures create poor workingconditions andto cycle at optimum speed, mechanical handling and removal equipment isrequired. Moreover, special equipment is often required to remove hotmoisture containing gases which ordinarily must be carried away from thesand core or mold to obtain the proper cure. Needless to say, such hightemperature sand forming systems are costly to construct, operate, andare not the most reliable.

It is accordingly a principal object of the present invention to providea foundry sand forming machine and a method which will operate at atemperature about 300 F. and yet still produce a mold or core in arelatively short cycle time.

Another principal object is the provision of a foundry mold or coremaking machine of simplified construction not requiring high maintenanceand fuel cost for the production of molds or cores.

Still another object is the provision of a machine and method for thecuring of molds or cores at a temperature which makes it possible to uselow temperature materials, such as aluminum, in the construction of themold or core box which maintain their strength and will not distort insuch temperature range. Moreover, materials such as the aforementionedaluminum can conduct heat about 4.5 times faster than cast iron, forexample.

3,439,733 Patented Apr. 22, 1969 "ice In the resin-catalysis systems,used to bond the sand grains together, burning generally occurs attemperatures in excess of 350 F. during the cure portion of the cycle.This generally produces cores of not the best quality and it can be seenthat it is desirable for a variety of reasons to maintain thetemperature of the heating medium employed of from about 250 to about350 F.

With such lower temperatures and, of course, less fuel consumption it ispossible to obtain a faster cure time than with the conventional hot boxgas flame impinged directly on the mold or core box. This can beaccomplished by the combination of a warm core box, which may be heatedcontinually with electrical heating elements, and hot air blown orpermeated through the core or mold producing a minimal cure time. Thewarm box cures a shell on the core while the hot air cures the inside ofthe core, thus permitting the mold or core to be removed from themachine during a very short cure cycle. It is, therefore, anotherprincipal object of the present invention to provide a foundry core ormold making machine and process which will utilize low energyconsumption and yet still have rapid cure cycles.

Yet another object is the provision of a core or mold making machine notrequiring water cooled sand-resin reservoirs which are employed toprevent the resins from reacting before entering the forming box.Needless to say, these cooling systems are expensive to build andmaintain. The object again is a simplified machine having theabove-noted advantages.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention,then comprises the features hereinafter fully described and particularlypointed out in the claims, the following description and the annexeddrawings setting forth in detail certain illustrative embodiments of theinvention, this being indicative, however, of but one of a few of thevarious ways in which the principles of the invention may be employed.

In said annexed drawings:

FIG. 1 is a side elevation of a machine in accordance with the presentinvention;

FIG. 2 is an end elevation of the machine shown in FIG. 1 as seen fromthe right thereof;

FIG. 3 is an enlarged horizontal section taken substantially on the line33 of FIG. 1 illustrating in detail the core box opening and closingmechanism of the machine;

FIG. 4 is a front elevation of the mechanism illustrated in FIG. 3 asseen from the bottom of such view;

FIG. 5 is a fragmentary vertical section taken substantially on the line5-5 of FIG. 3 with the core box opened;

FIG. 6 is an enlarged fragmentary vertical section taken substantiallyon the line 6-6 of FIG. 1 showing the sand-resin mix reservoir and thepower driven agitator disposed therewithin;

FIG' 7 is a schematic electrical wiring diagram illustrating the cycleof operation of the illustrated machine embodiment;

FIG. 8 is a schematic pneumatic piping diagram illustrating perhaps moreclearly the operating components of the illustrated machine;

FIG. 9 is an enlarged fragmentary vertical section of an exemplary corebox illustrating the vents for the sand blowing operation which are alsoutilized as ports for the admission of the hot air to permeate the blowncore; and

FIG. 10 is a schematic piping diagram illustrating the mechanism forheating the air and supplying the same to the core box.

3 MACHINE, GENERAL ARRANGEMENT Referring now to FIGS. 1 through 6 andmore particularly to FIGS. 1 and 2, the illustrated machine may includea base 1 having mounted thereon a bottom frame 2 upwardly from whichextend four corner frame .posts 3, 4, 5 and 6. A top frame 7 issupported thereon and includes two main horizontal beams 8 and 9. At therighthand side of the machine as seen in FIG. 1 there is provided twocylindrical hoppers 10 and 11, side-by-side, which may be supplied froman overhead conveyor system with a sand-resin mix, and a sand-catalystmix, respectively. Directly beneath each hopper is a rotating circulartable as indicated at 12 and 13 which may be driven by the motors 14 and15 through the transmissions 17 and 18, respectively. Posts 19 and 20support ploughs 21 and 22, respectively, extending radially of therotating table and such are effective to plough material falling ontothe tables from the hoppers off into a funnel 23 positionedtherebeneath. In the position of the machine shown in FIG. 1 the bottomof the funnel will be closed .by a slide cut-off plate 24. It can thusbe understood that the speed of the motors 14 and 15 will control theamount of materiel fed from the respective hoppers 10 and 11, and thusmay actively control the proportion of resin and catalyst in the mixbeing dumped into the hopper 23. Other blending or mixing devices may,of course, be employed for supplying the machine with the properlyblended sandresin mix.

Referring now momentarily to FIG. 6, it will be seen that the beams 8and 9 are each provided with a pair of depending rods as shown at 26 and27. Such rods may be secured to the beams by the fasteners shown, andthe lower ends of such rods are provided with laterally projecting axlesas shown at 28 and 29 on which are journalled flanged rollers 30 and 31,respectively. Horizontal rails 32 and 33 ride on the flanged rollersthus supported on the bottom of the rods suspended from the beams 8 and9. A pair of transverse frame members 34 and 35 extending between therails 32 and 33 support a sand-mix blow reservoir shown generally at 36.Reciprocation of the reservoir on the tops of the rollers 30 and 31 isobtained by the piston-cylinder assembly 37, the rod 38 of which isconnected to the reservoir at 39. Such pistoncylinder assembly 37 may bemounted on a support plate or bracket 40 extending between the framelegs 5 and 6 of the machine as seen more clearly in FIG. 2.

A blowhead shown generally at 42 in FIG. 1 is mounted on the top frame 7and is provided with a blow valve 43. The details of the blowhead andvalve are shown more clearly in FIG. 6. The blowhead 42 includes a maininlet passage 44 from the blow-valve 43 leading to the main horizontalpassage 45. The blowhead includes two laterally spaced blow inlets 46and 47 communicating with the horizontal passage 45. A tapped aperturein the blowhead may be provided with plug 48 as indicated while on theopposite side of the blowhead a pipe 49 is threaded into a similartapped aperture and may lead to a pre-fill valve. Each of the inletports 46 and 47 may be provided in conventional manner with aresiliently deformable peripheral sealing ring as indicated at 50.Centrally disposed between the inlet ports is an exhaust port 51 alsoprovided with a peripheral sealing ring 52 and a sand retaining screen53 which may be held in place by a centrall disposed fastener 54. Theport 51 communicates with horizontal passages 55 leading to exhaustvalve 56 shown in FIG. 1.

It can now be seen that the piston-cylinder assembly 37 which isoperative to recriprocate or shuttle the reservoir 36 will alternatelyposition such reservoir beneath the hopper 23 and beneath the blowhead42 to be clamped thereagainst by the core box therebeneath by means ofthe vertically movable table 58 and the clamp cylinder 59 in the base ofthe machine.

Referring again to FIG. 6, it will be seen that the reservoir 36comprises a cylinder 60 which is closed at each end by closure members61 and 62 which are sealed thereto by means of the O-rings indicated at63 and 64. The end closures are held in place by fasteners 65. The topof the cylinder 60 is provided with a large diameter verticallyextending fill-opening 66, the top of which is provided with a ring 67sealed by O-rinvg 68 to the flange 69. The end closures 61 and 62 areprovided with vertically extending passages 70 and 71 which in the blowposition of the resenvoir 36 are aligned with the air inlet openings 46and 47, respectively. Such passages 70 and 71 enter the interior of thereservoir behind annular deflector plates 72 and 73 secured to theinterior of the closures within the cylinder 60' by fasteners 74. Thedeflectors are provided with a slight clearance with the interior of thecylinder 60 as indicated at 75.

The bottom of the cylinder 60 is provided with a discharge port oropening 77 having a flaring mouth 78. The passage 77 is provided in aport member 79 which may be threaded into the bottom of the cylinder 60as well as the support plate 80'. The port members -fits within a bottomor blow-plate 81 which may be provided with vent openings as indicatedat 82.

Journalled in the closure 62 is the shaft 85 of agitator 86 which isdriven by motor 87. The shaft is driven by a flanged speed reducer 88secured to the outer side of the closure 62 by fasteners 89 and thetotally enclosed motor 87 is mounted directly on the speed reducer.

The agitator 86 secured to the end of the shaft 85 includes a diametralor transverse bar 90 with helical opposite hand blades 91 and 92extending from the opposite ends thereof. The helical blades fit closelyadjacent the interior of the cylinder 60 and rotation of the shaft 85 inthe direction of the arrow 93 will move the material within thereservoir in the directions of the arrows 94 and 95 or centrally towardthe discharge opening 77 and away from the annular air inlets at theopposite ends of the cylinder.

The sand mix may be dumped into the reservoir in the position beneaththe hopper 23 when the piston-cylinder assembly 37 is retracted. Theextension of the piston-cylinder assembly 37 will then move thereservoir to the position shown in FIGS. 1 and 6, and elevation of thetable 58 will then move the core box upwardly against the bottom of theblow-plate 81 to cause the entire reservoir to elevate sealing therespective inlet and discharge passages. When the machine is ready forthe blowing operation, air will be admitted from the blowvalve 43causing the sand within the reservoir to fluff up or fluidize and bedischarged through the mouth 78 of the port 71. Shortly thereafter theair pressure is exhausted through the ports 55 to the exhaust valve 56.The core box is then unclamped from the reservoir for the cure cycle,and the reservoir is then returned to the fill position.

The core box into which the material is blown through the port 77 maycomprise two laterally separable halves 9'8 and 99, the interior ofWhich may be patterned to form, for example, a worm gear housing core.As seen in FIGS. 3 and 4, the core box halves are mounted on the rods ofpiston-cylinder assemblies 101 and 102, and it can be seen thatextension of the assemblies will close the core box while retractionwill open the same for stripping of the core therefrom. Suchpiston-cylinder assemblies are supported on transverse frame members 103 and 104 which are interconnected by rods 105 and 106. The rods 105 and106 are supported on brackets 107 and 108 on the table 58 so that theentire core box opening and closing mechanism moves vertically with thetable.

The table 58 may be provided with a slot 111 in which is mounted a hotair pedestal 112 having an upwardly projecting core lightener 113thereon as indicated in FIG. 3, and a handle 114 may be connected to thepedestal. The details of the core box are shown more clearly in FIG. 9hereinafter described.

Attached to the blow-plate 81 and horizontally movable therewith is abracket 116 on which is mounted a vertically extending heat cure spacershown generally at 117. Such spacer includes a pad 118 on the bottomthereof having a laterally directed exhaust port 119 therein. Verticallyprojecting upwardly from the spacer 117 are four posts 120 which willunderlie the blowhead 42 when the piston-cylinder assembly 37 isretracted.

EXEM'PLARY CO'RE BOX Referring now to FIG. 9, there is illustrated onetype of core box which may be employed with the present invention, suchbeing for the production of a steering 8 gear housing. Each core boxhalf will be substantially identical in form, and accordingly only onecore box half will be described in detail. The core box half 99 includesa core box mounting plate '122 on which the patterned interior 123 ofthe box is secured. The patterned portion 123 of the box may include acentral horizontal partition 124 dividing the interiorinto two chambers125 and 1-26. Screened vent openings 127 are po sitioned throughout thepatterned portion of the core box communicating with the chambers 125and 126. The arrangement and size of such vents is, of course, designedto obtain a properly compacted blown sand article within the box.

Secured to the exterior of the core box mounting plate is a heatermounting plate 130 which has positioned therein ring heaters of theelectrical type shown at 131 and 132. The somewhat larger ring heater131 may, for example, be an 1800 watt-1'20 volt heater, while thesmaller heater 132 may be 750 watts-120 volts. A plate 133 of insulatingmaterial is interposed between the heater mounting plate 130 and themounting plate 134 for the core box clamps which will move the core boxhalves 98 and 99 laterally to open same and firmly press them togetherfor the clamped blow cure position.

The lightener 113 is provided with a vertical passage 136 and has aplurality of radially extending screened ports 137 as well as a topscreened port 13 8 providing communication between the vertical passageand the inte-rior of the core box. The vertical passage 1 36 at itslower end communicates with passage 139 in the hot air pedestal 112.

During the blowing operation the core box halves will be clampedtogether and the table 58 will be elevated to clamp the thus formed corebox directly beneath the blow-plate 81, and the sand-resin mix will beblown through the port 77 into the top opening 140 of the core box, andthe screened vents '52 in the blow-plate will serve to vent the upperend of the core. The air passes through the screened vents into thechambers 125 and 12-6 in each core box half and is vented therefromthrough ports 141 and 142 shown in FIG. 9. Similar ports 143 and 144 areprovided in the chambers of the core box half 98 so that during theblowing operation air will be vented from the core box through the fiveports 139, 140, 141, 1'42, 143 and 144. A thermocouple 14 5 is locatedin the passage 139 of the hot air pedestal 112 to measure thetemperature ofthe air therein, and a thermocouple 146 may be located inthe wall of the core box to measure the box temperature.

MACHINE CONTROL SYSTEM Referring now to FIGS. 7 and '8, there isillustrated one of a wide variety of control systems which may beemployed to operate the illustrated machine. Referring first to FIG. 7,a start push button 150 may be employed to energize relay 151 to closeswitches 152, 153, 154 and 1'55. The switch 152 energizes horizontalclamp solenoid 156 shifting valve 157 seen in FIG. 8 supplying pneumaticpressure from line 158 to the blind ends of the 7 clamp piston-cylinderassemblies 101 and 102, causing the core box to clamp closed.

The closing of switch contacts 153 energizes fill solenoid 160 throughmanually operated selector switch 161 to shift valves 162 supplyingpneumatic pressure to the blind end of the carriage cylinder 37,shifting the reservoir 36 from the fill to the blow position. Theclosing of switch contacts 154 then permits the relay 151 to bede-energized by manual stop push button 163. The closing of contacts 155by the relay 151 will then energize the vertical clamp solenoid 164 whenthe limit switch 165 is closed. The limit switch 165 will be closed bythe proper position of the reservoir 36 in registry with the blowhead42. The solenoid 164 shifts valve 166 to supply pressure from the line158 to the bottom of the clamp cylinder 59 through line 168 havingtherein check valve 169, flow control valve 170, and shutoff valve 171.This application of pressure to the bottom of the clamp piston-cylinderassembly causes the table 58 with the clamped closed core box thereon toelevate against the blow-plate on the bottom of the reservoir 36elevating the same against the blowhead 42, clamping the assembly in avertically aligned position. When proper clamp pressure has beenobtained, pressure switch 173 seen at the top of FIG. 7 will be closedenergizing relay 174 which will close switch contacts 175, 176 and 177.The switch energizes vertical clamp pressure limit solenoid 178 whichwill shift valve 179 supplying pressure from line 158 to line 180,shifting shut-off valve 171. The closing of contacts 176 energizespre-fill solenoid 182 shifting valve 183. The shifting of valve 183 inturn shifts valve 184 in three-quarter inch line 185 to supply air fromthree inch line 186 to the blowhead through the pre-fill pipe 49illustrated in FIG. 6. This is omrative to force the sand through thedischarge opening into the closed core box therebeneath, andsimultaneously with the energization of the solenoid 182, pre-fill timer188 as well as agitator timer 189 are also energized. Relay 190controlling switch contacts 191 which in turn energize motor 87 drivingthe agitator. The timer 188 will time out at a very short interval andwill then energize the blow timer 193 through the line 194. This willthen close the circuitry to the blow solenoid 195 shifting valve 196 toopen the blow valve 43 connected to the three inch line 186 to ram orpack the sand firmly into the core box. The blow time as determined bythe timer 193 may be approximately one-quarter of a second, and when thetimer 193 thus times out, the solenoid 195 will be deenergizedpermitting the shuttle valve 197 to open the exhaust valve 56.

As seen in FIG. 8, a differential safety valve 200 is connected to theblowhead 42 or sand reservoir 36 by means of a one-quarter inch line 201and is connected to a three-quarter inch line 203 communicating withlines 168 and 204. Pilot operated valve 205 is effective to shiftshutoff valve 206 to connect line 204 to cylinder 59 to cause rapidelevation of table 58. When the blow timer 193 times out, the relay 208will be energized through selector switch 209 which in turn closesswitch contacts 210 energizing relay 211. Relay 211 then closes switchcontacts 212 to energize heat timer 213 and heat solenoid 214. Heatsolenoid 214 shifts valve 215 in turn shifting threeway valve 216. Theshifting of valve 216 connects heat line 217 to line 218. The three-wayvalve 216 in its normal position connects the line 218 to the exhaustline 219.

The heat timer 213 may have a maximum time cycle of approximately twoand one-half minutes although it will be appreciated that cores may becured in considerably less time as, for example, approximately twenty tothirty seconds. It is noted that various manual switches may bepositioned throughout the circuit such as the heat selector switch 220and the repeat blow switch 221. At the conclusion of the heat cyclecontrolled by the setting of the timer 213, the relay 211 may then beemployed to de-encrgize or repeat the cycle.

7 BLOW HEAT CURE-CONTROL Referring now to FIG. 10, electricity issupplied to the heater plates 130 of the respective core box halvesthrough lines 223 and 224, and controller operated switch 225 in line223 will turn such heaters on and off. The controller 226 may simply beset by means of the dial 227 at the desired temperature. The controller226 also controls gas valve 228 which regulates a gas burner 229producing, for example, 50,000 Btu. The burner 229 provides heat toheater 230 receiving air from a convenient plant source from line 231through pressure regulator 232. Such hot air heater may be a simple heatexchanger much like the hot water heater wherein the air is passedthrough coils or fin-tubes to be heated. From the heat exchanger the hotair serving as an accelerator for curing the sand passes into the line217 through a flow rate controlling manometer 233 having pressureregulators on each side thereof. During the heat cycle, the valve 216will be positioned then to pass the hot air into line 218 into the corebox as indicated. A thermocouple 234 is provided in the line 217 tomonitor the temperature of the air leaving the heater 230, and thisthermocouple together with the thermocouple 146 measuring the boxtemperature and the thermocouple 145 measuring the entering airtemperature may be connected to a switch box 235 feeding the informationthus obtained back to the controller 226 which in turn regulates the airand electrical heater temperatures.

It can now be seen that during the blow operation, the air will passthrough the ports 141, 142, 139, 144 and 14 3 into the line 218 whichwill then be exhausted through line 219 when the three-way valve 216 ispositioned with the solenoid thereof de-energized. However, during thecure portion of the cycle such solenoid will be energized shifting thevalve to permit the hot air then to flow back through the line 218 andto permeate the blown core through the multiplicity of screened ventopenings in the core box.

OP-ERATION Briefly, the operation of the illustrated machine is asfollows. Metered amounts of sand are fed from the hoppers and 11containing, respectively, measured amounts of resin and catalyst intothe hopper 23 to drop into the reservoir 36 positioned therebeneath bythe retraction of the piston-cylinder assembly 37. With the core boxclosed by the clamps 101 and 102, the piston-cylinder 37 is thenextended to the center line of the machine beneath the blowhead 42. Theclamp cylinder 59 is then elevated to elevate the table and the closedcore box to clamp the latter against the reservoir 36 in turn to clampthe reservoir 8 to the blowhead. The blow cycle is then initiated andthe sand within the reservoir is transported into the core box to bepacked firmly therein with air passing from the vents through the lines218 and 219 to atmosphere.

At this point the core box and core box clamps, still closed, arelowered slightly to permit the reservoir to be retracted to the fillposition beneath the hopper 23, and the vertical heat cure spacer 117 isthen positioned in the center line of the machine positioning the pad118 above the top of the core box. The core box is then again verticallyclamped against the pad 118 and the spacer 117 against the blowhead.

The three-way valve 216 is now shifted. The hot air then passes throughthe line 218 into the four compartments common to the core box ventsthrough the ports 14-1, 1142, 143 and 144, as well as the port 139leading to the lightener 113. The hot air then passes through the ventsand permeates the blown core, and then passes outwardly through thescreened port of passage 119 in the pad 1'18. The passage 119 may beconnected to suitable exhaust fans or the like to be conducted out ofthe room in which the machine is operating since both moisture anddeleterious gases may be included in such exhaust. The driving of themoisture from the core has been found to be extremely helpful inaccelerating the cure by the method herein disclosed.

After the predetermined short cure cycle in which the hot air ispermeated through the mold or core, the valve 216 is again shifted andthe box is then unclamped by the lowering of the table and thenunclamped horizontally and the core is then removed manually orautomatically. The box may then be blown clean, sprayed, and then thereservoir is repositioned in the center line of the machine for a repeatof the above-described cycle.

For example, the hot air heater 230 may elevate the compressed airtemperature from about 85 F. to about 400 F. as measured by thethermocouple 234. The temperature of the air will then drop to about 300F. or just below that as it enters the core box as measured by thethermocouple 145. The temperature of the core box as maintained by thering heaters 131 and 132 may be maintained at the desired levelthroughout the cycle of the machine.

SAND MIXTURES obtained at a maximum box and air temperature of 300 F.

Type of Percent 4 Acid Cone, Percent Cure time Bench life resin resin toType acid percent acid to (sec.) (mim) sand resin 12241.. 2 K3PO 80 3025-30 20-25 A-200 35 25-30 18-22 40 25-30 -20 50 25-30 10-15 YEP-10B 20OP40B 25-30 10 80 H5P0 K31 0; at 85%..- 10 EP-40B 25 25-30 10 90 H3PO4EP-O-O 50 Solids 19 10 30 30 10 H PO; 85 30 25-30 10 35 20-25 10 18-22 816-20 5 U R-l51-.- 2 EP-40O 50 Solids 30 15-20 10-15 EP-40B Solids 3015-20 10 Solids 30 13-15 7 A-200 2 PzO5-D1y a. 30 35 10-15 3P0; 30 25-3010-12 Resins A200, 122-0, and CR- lSl are commercially available fromArcher-Daniels-Midland Company (ADM Chemicals, Foundry ProductsDivision, Cleveland, Ohio). Resin A200 is a furfural alcohol basematerial and is classed as a cold or air set material. Resin 122-C is afurfural alcohol urea formaldehyde resin classed as a hot box material,meaning that it is a material with long pot life requiring curingtemperatures around 600 degrees Fahrenheit. Resin CR-151 is a ureamodified phenolic also classed as a hot box material.

Some of the binder materials used would be suitable for either a hotbox, warm box, or air set use, depending upon the amount and type ofcatalyst used. The following are typical of some of the acid catalyststhat are used:

(1) H PO ,Phosphoric acid 80% and 85% concentration (2) P O -Phosphoricacid anhydride (dry powder) (3) EP 40-B-Liquid at 100% solids (4) EP40CWater solution EP 40-D at 50% solids (5) EP 40D--Solid acid at 100%solids (6) EP 40-=E-Super H PO at 77% solids Using hot air to cure acold-set resin may seem to be somewhat of an anomaly, but it will beappreciated that such cold-set resins will cure at room temperature andthat the hot air simply accelerates the process. It is also to be notedthat the cure time may be shortened by varying the percentage ofcatalyst in each example with the larger the percent of catalyst usuallyshortening the cure time. However, the bench life of the mixed sand alsobecomes shorter as the cure time is shortened which requires a machinehaving a fairly rapid cycle of operation. The term bench life may bedefined as a time limit within which satisfactory cores can be madeafter the resin is mixed with the catalyst and sand.

It can now be seen that there is provided a sand forming machine andmethod having a wide variety of advantages. For example, the cost ofcore boxes may be reduced since existing hot box systems usuallyemploying furan resins require temperatures in the vicinity of 600 to700 F. With the present process, requiring temperatures of only about300 F. It is possible to use low temperature materials in construcingmold and core boxes. Also, in such hot box systems, water cooling isusually required to prevent the resins from reacting before entering thebox, and, needless to say, these cooling systems are expensive anddifficult to maintain. The less heat required for the present processnot only reduces the amount of energy required to form the sandarticles, but also enables greater accuracy of the article to beobtained. This is, of course, due to the fact that high temperatures maywarp or distort the patterned box, and, of course, the use of gasburners which impinge directly upon such boxes may cause uneven heatingif but one of the burners is not operating properly. A distorted boxmay, of course, not only cause inaccurate cores, but also broken orimproperly cured cores.

With the short cure times set forth above it is, of course, apparentthat relatively high production is possible at lower temperatures whichcreate better and safer working conditions. Moreover, these lowertemperatures will increase the box life as well as the reliability ofthe system. It is also apparent that a more simplified machine withoutthe complex cooling and heaters may be provided since a single hot airheater may provide the hot air for an entire bank of machines.

Moreover, resin-catalyst systems which are used to bond the sand grainstogether may burn at temperatures in excess of 350 F. during the curingcycle, and accordingly if the temperatures are maintained below 300 F.such burning does not occur. Such low temperatures permit the use ofaluminum in the construction of the boxes, and since aluminum canconduct heat approximately 4.5 times faster than cast iron, a warm corebox may be maintained with little electrical heat energy. The Warm corebox and the hot air blown or permeated through the core will thusproduce accurate cores in a minimal cure time. The warm box tends tocure a shell on the sand article while the hot air permeated through theinterior of the article cures the inside thereof. However, certain areasof the core are not cured when the core is first removed from the corebox, but within minutes the core will be completely cured.

Other modes of applying the principles of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims or the equivalent of suchbe employed.

We, therefore, particularly point out and distinctly claim as ourinvention:

1. A core blowing machine comprising a sand-resin mix reservoir having acentral discharge opening therein, means to support a core box clampedbeneath said sand resin mix reservoir, means to blow sand from saidreservoir to such core box through such discharge opening, and means topermeate a low temperature accelerator through such core boxsubstantially to cure the core within the same, said reservoir includinga power-driven agitator therein operative to increase the bench life ofsuch sand-resin mix, said agitator being in the form of a screw typeconveyor operative to move such mix toward such central dischargeopening of said reservoir.

2. A core blowing machine as set forth in claim 1 wherein such dischargeopening is located in the bottom of said reservoir and said screw typeconveyor comprises opposite hand screw flights laterally on oppositesides thereof.

3. A core blowing machine as set forth in claim 1 wherein said reservoiris mounted for horizontal shuttling movement, a pressure pad connectedto said reservoir for movement therewith and having an exhaust porttherein, and means to clamp such core box against said pad prior topermeating such accelerator therethrough.

4. A core blowing machine as set forth in claim 1 wherein such core boxis provided with a plurality of vents to permit the blowing of suchsand-resin mix therein, such vents being utilized to permeate suchaccelerator through the core box after such blowing operation 5. Afoundry molding machine comprising a blowhead, a sand reservoir, meansoperative to clamp a core box and the like to said reservoir and saidreservoir to said head, vent means connected to such box, and means toswitch said vent means from exhaust to a source of an accelerator underpressure after sand is blown within such box to cause the same topermeate the sand within such box and accelerate curing of the sand.

6. A foundry molding machine as set forth in claim 5 including means toremove said reservoir from such box and to replace the same with avented pressure pad prior to permeating such accelerator through thebox.

7. A foundry molding machine as set forth in claim 5 including meansoperative to heat the box.

8. A foundry molding machine as set forth in claim 5 including meansoperative to fill said reservoir With proportional amounts of sandcontaining a resin and catalyst.

9. A foundry molding machine as set forth in claim 5 wherein saidreservoir is mounted for horizontal shuttling movement, a pressure padconnected to said reservoir for shuttling movement therewith and havingan exhaust opening therein, and means to clamp such box to said pressurepad after the sand is blown therein and prior to the permeating of suchaccelerator therethrough.

(References on following page) References Cited UNITED STATES PATENTSDemmler 164-234 Herbruggen 164201 Herbruggen 164-201 Shallenberger eta1. 164200 X Hatch 164-402 X Miller 164-201 1 2 FOREIGN PATENTS 11/1930Germany. 4/1932 Germany.

5 J. SPENCER OVERHOLSER, Primary Examiner.

EUGENE MAR, Assistant Examiner.

US. Cl. X.R. 16421, 234

